The present invention relates to a process for the lateral positioning of a member relative to a joint formed between two metal surfaces and having discontinuities, as well as to an apparatus for performing this process.
More specifically, the present invention relates to the problem of the automatic lateral positioning of a member, such as a welding torch relative to the joint separating two members to be welded, when the latter are held in position by weld points made beforehand. These weld points are usually produced manually in a random manner, so that their spacing and shape vary. These weld points consequently form discontinuities of the joint formed between the two members, which are distributed in a random manner along the joint.
It is obvious that the presence of these weld points along the joint separating the two members to be welded may be prejudicial to the operation of a welding head equipped with an apparatus ensuring its automatic lateral positioning. Thus, the automatic positioning apparatus may lose the joint at the moment of passage of the weld point and will therefore guide the welding torch outside the working area.
These risks are particularly high when the automatic lateral positioning apparatus uses eddy current transducers, because the latter react in a very sensitive manner to the weld points constituting a discontinuity of the joint separating the metal surfaces, i.e. a short-circuit between the surfaces of the metal sheets to be welded. Therefore, the welding torch cannot be directly controlled as a function of the data supplied by the transducers, because this would lead to very significant position variations at the passage of the weld points.
Obviously, the application to the welding of two metal sheets is not limitative and the invention can be used for solving any lateral positioning problem of a member relative to a joint formed between two surfaces and having discontinuities.
To solve the difficulty mentioned hereinbefore, it is possible to envisage the recording of the position of the discontinuities along the joint during a prewelding operation. However, this operation is long and costly, so that it is considered inappropriate for the problem in question.